QThe glass in my first-floor windows gets a spotted residue when it rains. I've tried window cleaner and vinegar, but they don't remove the residue. Any suggestions? -- Tony

AAs you probably know, rainwater these days contains impurities, including acid compounds. White vinegar diluted with an equal portion of warm water makes an excellent window cleaner and will often remove mineral deposits or hard-water spots that other cleaners won't. If you have used a weaker vinegar solution, try again with this formula. Apply it with a spray bottle, sponge or soft brush and wipe dry with a soft cloth. If that still fails, buy the widest razor-blade scraper you can find at a paint store and try scraping off the residue. Wet the glass before scraping and use care to avoid scratches. These scrapers are often used to remove paint or other difficult deposits from glass.

Window-cleaning solutions can also be made by diluting any one of the following in warm water: household ammonia, washing soda, baking soda or borax. Use about one tablespoon of compound per quart of water.

Some general window-cleaning tips: Try not to wash windows when the sun is shining on them -- they dry too fast and sometimes get streaks. Some window cleaners use balled-up newspaper or paper towels to dry windows, but a soft cloth or cotton towel is better. Professional window cleaners generally use a squeegee to dry windows -- it is fast and leaves a clean, streak-free surface.

Our asphalt driveway has numerous cracks, most about 1/4-inch wide. How can I best repair these cracks and what type of seal coat should I use? -- Lee

Cracks in asphalt, or blacktop, driveways up to about 1/8-inch wide can be sealed with a combination sealer and filler such as Weatherbeater Premium. Cracks larger than 1/8-inch must be patched individually. Patching compounds sold in caulking-gun cartridges are often used on cracks of this size. I have gotten the best results with silicone-based patching compounds (about $3 per 10-ounce tube), but don't expect any patching compound to hold up for more than a few years. Patching should be done before you apply the sealer coat.

I prefer coal-tar emulsion for sealing asphalt driveways; the sealer mentioned above is this type. A coat of sealer every three years is usually adequate.

The vinyl soffits on my house have turned black. I was told not to power wash because the water might get into the attic and damage the insulation. Can you help? -- T. Roche

The black stains are probably mildew. Here is a formula for a cleaner that should remove mildew and dirt from vinyl soffits (the underside of the roof overhang) and vinyl siding. Mix 1/3-cup non-ammoniated household detergent, 2/3-cup trisodium phosphate and one quart of chlorine bleach in a gallon of water. Be careful not to use an ammoniated detergent, which will produce a dangerous gas if mixed with chlorine bleach.

Apply the solution with a long-handled scrub brush and rinse with clear water. Wear goggles, gloves and long sleeves, and watch out for drips when working on overhead surfaces such as these.

A contractor installed slate on my concrete front porch, and told me to seal it to prevent water damage. What should I seal it with? Also, should I put caulk along the edge where the slate meets the brick siding of the house? -- P. Edwards

It would have been a good idea to ask the contractor if he had a specific sealer in mind. However, masonry sealers suitable for slate are sold at most home centers and building-supply outlets. Proseal Slate Sealer is a well-known brand. Make sure you get a sealer suitable for outdoor use.

A sealer will help protect the porch surface from weather and stains, make it easier to clean, and enhance the color of the slate.

You should caulk the joint with the siding with a high-quality silicone caulk. This will help keep water from getting under the slate and causing problems.

Questions and comments should be sent to Gene Austin, 1730 Blue Bell Pike, Blue Bell, Pa. 19422. Send e-mail to doit861@aol.com. Questions cannot be answered personally.